Field of the Invention
The present invention relates to a lens barrel installed in an image pickup apparatus, such as a digital camera, a digital video camera, and relates to an image pickup apparatus equipped with the lens barrel. Moreover, the present invention relates to a lens driving device of a digital camera equipped with a zoom lens barrel, and relates to an image pickup apparatus equipped with the lens driving device.
Description of the Related Art
There are some known image pickup apparatus, such as digital cameras, that enable zooming and focusing by moving lenses in accordance with a rotary operation of an operation ring provided on an outside periphery of a lens barrel. For example, a configuration that enables electric zoom drive and manual zoom drive that are selected using a changeover switch provided on a side portion of a lens barrel is disclosed (Japanese Laid-Open Patent Publication (Kokai) No. 2008-58914 (JP 2008-58914A), and Japanese Laid-Open Patent Publication (Kokai) No. 2006-259130 (JP 2006-259130A)).
Moreover, a configuration that enables an operation with feeling close to a manual operation by detecting a rotation amount of an operation ring and driving a lens electrically corresponding to the detected rotation amount is disclosed (Japanese Laid-Open Patent Publication (Kokai) No. H5-11163 (JP H5-11163A)). Furthermore, a configuration with a gear mechanism that receives two inputs to a lens barrel is disclosed (Japanese Laid-Open Patent Publication (Kokai) No. 2012-42619 (JP 2012-42619A)). The gear mechanism enables zoom drives by manual operation of an operation ring and by electric drive without providing a changeover switch.
Moreover, Japanese Laid-Open Patent Publication (Kokai) No. 2013-083775 (JP 2013-083775A) discloses a technique that transfers rotational force of a rotary operation of an operation ring to a zoom drive system through a clutch gear when a changeover switch between electric drive and manual drive is switched to the manual drive. This technique needs to operate the operation ring with rotary torque more than detent torque of a motor.
However, since the configurations in the above-mentioned JP 2008-58914A and JP 2006-259130A require a gear train that transfers the rotation of the operation ring to the lens barrel and the switching mechanism for moving a gear in an axial direction, the number of parts becomes large, which prevents the image pickup apparatus in addition to the lens barrel from miniaturizing.
Moreover, since the configuration in the above-mentioned JP H5-11163A accumulates an influence of backlash of the switching mechanism to the gear teeth when the rotation of the operation ring is transferred to the lens barrel through the gear train, the effect of shakiness of the switching mechanism to a gear tooth, time lag may occur between a rotary-operation timing of the operation ring and a drive timing of the lens.
Furthermore, although the configuration in the above-mentioned JP 2012-42619A solves the problem of the switching mechanism, a large space is needed in order to install the gearing mechanism that receives the two inputs, which prevents the image pickup apparatus in addition to the lens barrel from miniaturizing and thinning.
Moreover, since the technique in JP 2013-083775A makes the feeling of the manual rotary operation of the operation ring heavy because of friction of the gear train including the motor, the operability of the operation ring drops. And since the clutch gear is needed in the gear train, the configuration is complicated. Furthermore, when a worm is installed between the motor and the gear train, for example, an engagement relation (the number of threads) must be considered in order to rotate the motor smoothly by transmitting the rotational force of the operation ring to the motor through the gear train, which restricts the design.